1. Field of the Invention
The present invention relates to a data communication system capable of transmitting and receiving a frame, which contains a preamble, an SFD, and data in that order, between communication apparatuses, a method of optimizing the preamble length of the data communication system, and a communication apparatus.
2. Description of the Related Art
In general, a data communication system makes data in the form of a frame (or package) and transmits and receives the data. As shown in FIG. 1, the frame has a structure in which a preamble, a start frame delimiter (SFD), a data length, an address, data, and a cyclical redundancy check (CRC) are positioned in that order from a header. The preamble is a signal pattern to allow a receiver to recognize the beginning of the frame and to provide synchronization timing for the reception of the frame. The SFD is a recognition bit pattern provided between the preamble and the data. The data length represents a length of effective data (address, data, and CRC) in the frame. The address represents the address of the receiver, and may contain the address of a transmitter. The data actually refers to a data body. The CRC is used to check errors occurring during the transmission of the frame.
Since a communication apparatus at a transmitting side transmits a frame in the above-described order from the preamble of the frame, when a communication apparatus at a receiving side receives an arrived frame, the communication apparatus at the receiving side acquires synchronization timing of each bit following the preamble of the frame by detecting the preamble positioned at the header of the frame, and determines according to the synchronization timing if the bit pattern of the next SFD is detected as shown in FIG. 2. If the bit pattern of the SFD has been detected, the data length, the address, the data, and the CRC, which follow the SFD, are acquired and stored.